Timing apparatus



Oct. 10, 1944.

T. B. GIBBS 2,360,053

TIMING APPARATUS 4 Sheets-Sheet l 1 Filed March 24, 1941 INVENIOR.7210/22 as Z3. Gbb',

Wi W Oct. 10, 1944. 555 2,360,053

TIMING APPARATUS Filed March 24, 1941 4 Sheets-Sheet 2 INVENTOR. ThomasB Gibbs Oct, 10, 1944. T @1555 2,360,053

' I'IMING APPARATUS Filed March 24, 1941 4 Sheets-Sheet 5 Oct. 10, 1944.T. B. GIBBS TIMING APPARATUS 4 Sheets-Sheet 4 Filed March 24, 1941 RUNINV ENT OR.

VBY

Patented Oct. 10, 1944 TIMING APPARATUS i Thomas B. Gibbs, Delavan,Wis., assignor, by

mesne assignments, to George W. Borg Corporation, Chicago, 111., acorporation of Delaware Application March 24, 1941, Serial No. 385,029

28 Claims. (Cl. 73-6) 1 The present invention relates in general totiming apparatus, and more in particular to apparatus for timing orchecking the rate of mechanical fuses such a are used in shells. A fuseof this type includes a clockwork mechanism which is driven by powerdeveloped by centrifugal force acting on a pair of weights duringrotation of the shell in its flight. The -clockwork mechanism can bedriven from another power source before the fuse is completelyassembled, but the rotation of the shell affects the rate, andconsequently it is desirable to carry out the timing operation while thefuse is undergoing rotation.

A specific object of the invention, therefore, is

to provide an apparatus for timing a fuse of the mechanical or clockworktype while it is being rotated at a high speed, approximately 16,200 R.P. M., in order to simulate its operation when the shell in which itwill eventually be used is fired.

Other objects relate in general to the production of an improved timingapparatus having features of advantage in timing fuses and for otherpurposes.

The invention will be described hereinafter in connection with theaccompanying drawings, in which Fig. 1 is a sectional view of a chuckfor holding a fuse while it is being rotated, together with a guard andparts of an optical system which are mounted thereon;

Fig. 2 is a top view of a mechanical type of fuse;

Figs. 3 and 4 show details of the slot which is milled in one of thefuse plates;

Fig. 5 is a view showing the relation of the light source to thespinning motor and guard when a modified optical system is used;

Fig. 6 is a sectional view through the guard shown in Fig. 5, showingdetails 'of the chuck and modified optical system;

Fig. 7 shows details of the slots in the plates of a fuse by which it isadapted to be timed with the optical system shown in Figs. 5 and 6; and

Figs. 8 and 9 are diagrammatic circuit drawings of a complete fusetiming equipment.

Referring to Fig. 1, the reference numeral I indicates a portion of thetop of a table where the timing operations are performed. The operatorsits in front of this table and on it are mounted those parts of theequipment which require her attention, as well as other partsnecessarily associated therewith.

Beneath the table top the motor 2 is mounted in suitable manner, withits shaft 3 vertical and projecting upward through an opening in thetable top. The motor 2 is preferably of a type having a high startingtorque and adapted to run on three phase alternating current atsynchronous speed. 1

The chuck for holding the fuse is mounted on the end of the motor shaftand comprises two main parts, a receptacle for receiving the fuse and acap for locking the fuse in position in the receptacle. The receptaclepart of the chuck includes a flanged base portion 4, having an openingtherein for receiving the shaft 3. The part 4 fits tightly on the shaftso as to be rotated thereby when the motor is running. Associated withthe base 4 there is a cylindrical part 6, flanged internally, and acup-shaped part 1. These parts are secured to the base 4 by means ofscrews such as l0, as shown in the drawings.

- 6 and I for receiving the open end of the cap 8.

There is also an annular space between the cylin drical member 6 and thebase 4 and in this space there is fitted a flanged cylindrical member 5.The member 5 is slidable up and downand is normally held with itsinternal flange in engagement with the circular stop plate l3 by springssuch as 9. The plate I3 is secured to the base member 4. The member 5has a spline II which slides in the groove l2 and prevents rotation ofmember 5 relative to the other parts of the chuck.

The cap 8 is a cylindrical shell open at the lower end and partly closedat the upper end by an inwardly extending annular flange, as seenclearly in the drawings. The cap is removable from the chuck. Whenassembled in place the open end of the cap enters the annular spacebetween the members 6 and l, where it is held by means of. a pluralityof bayonet joints. One of these joints is shown on the section line inFig. 1, and comprises the pin ll, rigidly fixed in the member 6, and thecooperating slot 1 6 which is cut in the skirt of cap 8. The shape ofthe slots can be seen from the dotted line showing of the next adjacentjoint comprising pin l8 and slot I9. It will be understood that inpractice there will be preferably three or four of these joints, equallyspaced, and arranged to alternate with the screws such as I0.

A fuse of the type previously referred to is indicatedat l4. With thecap 8 removed, the fuse may be placed in the annular seat 20 which isformed at the upper end of the sliding member 5. The seat is providedwith a projection (not shown) which fits in the recess ii at the lowerend of the fuse, and accordingly the fuse must be turned until therecess and projection are in alignment before it can be properly seated.Th arrangement described prevents rotation of the fuse in the chuck andalso insures that it will be placed in the chuck in the correct angularposition as requiredby the optical system.

When the fuse has been properly positioned initsseatthecaplmaybeputonandisrotated imtil the pins such as 18 enter the slots such as IS. Theupper seat 2| formed in the flange at the top of the cap thereuponengages the top of the fuse. The cap is now pressed down as far as itwill go, the cylindrical member moving downward against the tension ofsprings 9, and is then rotated in a clockwise direction as seen from thetop in order to engage the bayonet joints. The cap is thus locked inposition and the fuse I4 is securely held between the lower seat 23 andthe upper seat 2|.

The guard is indicated at 22 and is preferably a casting havingsubstantial walls so as to provide adequatep'rotection to the operator.The guard is conveniently made large enough to afford space for mountingthe first amplifier stage and is provided with a partition 23 whichdivides the interior into a guard section proper, which surrounds thechuck, and a housing section in which the parts of the first amplifierstage are located. These parts are not shown in Fig. 1, since themounting arrangement may follow known practice.

The guard 22 is hinged to the table top, as indicated at 26. Theprovision of the hinge enables the guard to be rotated in a clockwisedirection, as seen in Fig. l, in order to expose the chuck and give theoperator access thereto. A handle may be ,providedat the side of theguard to facilitate its manipulation by the operator, or any othersuitable means may be provided for this purpose. An opening 25 near thehinge permits the installation of a flexible cable carrying thenecessary conductors for connecting with the amplifier. When the guardis in closed position, as shown in the drawings, it depresses a pin 25and thus closes a switch comprising the contact springs 21 and 28.

The optical system includes a lamp 30 which is moimted in a suitablesocket 3|. The latter is supported on a circular glass plate 32, which.in

turn is supported on the interior wall of the guard, as shown. A mask 33isattached to the lamp socket and surrounds the lamp 30 in order toprevent general illumination of the interior of the guard. The circuitconnections to the lamp preferably include two fine bare copper wireswhich extend along the top of the glass plate from the lamp socket tothe opening 24 through which they pass into the amplifier housing, wherethey connect to conductors coming from a suitable source of current forlighting the lamp. These fine wires are not shown, but it will beunderstood that they may be secured to the glass plate in spacedrelation by means of some transparent cement or gum such as shellac.Suitable sleeves are provided at the opening 24 and beyond.

The remainder of the optical system comprises a photo-cell 34, anannular mirror 36, and a refiecting surface of the fuse. The photo-cell34 has a socket 35, which is mounted on the partition 23. The mirror issupported on the inp terior wall of the guard like the glass plate 32.In this connection it will be understood that the members 31 and 38 arepreferably split cylinders of resilient material which are tensionedoutwardly and thus grip the interior wall of the guard. The mirror 36may be of metal and has a polished reflecting surface.

The arrangement of the fuse and its reflecting surface may be explainedwith reference to Figs. 2, '3, and 4. Fig. 2 is a general view of thefuse as seen from the top and shows the plate 40 having openings thereinthrough which parts of the clockwork mechanism may be seen. These partsinclude the oscillatable balance or pallet arm 44, the two pallets 45and 46, and the escape wheel 41. The pallet arm 44 is located in arecess in the plate 40 and when the clockwork mechanism is running itoscillates back and forth across the opening 48. The reflecting surfaceis indicated at 43 and is formed by milling a slot 42 in plate 4|, asshown in Figs. 3 and 4. This slot is so located that when the fuse isassembled the slot is centrally disposed with respect to the opening 48in plate 40 and is covered by the end of the pallet arm 44 when thelatter is in its central or at rest position. During oscillations of.the pallet arm the reflecting surface 43 is exposed to light from thelamp 30 through the opening 48, therefore, but during each beat of thepallet arm, when it passes through its midposition, the light is cutoff.

It will thus be seen that the arrangement described provides fortransmitting light from the lamp 30 by way of the opening 48, thereflecting surface 43 (when not covered by 44), the opening 50 in thewall of the cap 8, the annual mirror 36, and the transparent glass plate32 to the photo-cell 34. When the,.iuse is rotated the path of the lightrotates also, and generates a conical figure having its apexsubstantially at the cathode of the photo-cell. The light path isinterrupted by the pallet arm of the fuse as it oscillates, and thepallet arm thus sends light impulses to the photo-cell which areemployed to produce current variations in the circuit of the photo-cell.Although the rotating light path periodically crosses the wirespreviously mentioned as leading to the lamp socket 3!, these wires areso small that the transmission of light impulses by the oscillatingpallet arm is not interfered with. Any photo-cell currents that aregenerated as a result of the partial interception of the light by thewires have a frequency which is difierent from that of the currentsgenerated by the light impulses transmitted by the oscillating palletarm, and are filtered out, as will be described subsequently.

It will be observed that the angular positioning of the fuse in its seatby the recess l5 insures that whenthe fuse is placed in the chuck thereflecting surface 43 will be adjacent to the opening 58in the cap 8.

Reference may. now be made to Figs. 5, 6, and '7, for a briefdescription of the modification shown in these figures.

Fig. 5 shows the general arrangement of -the guard, motor, and lightsource. The'motor 55 is suitably mounted beneath the table top 54,

as indicated in the drawings. Above the table top and suitably hingedthereto is the guard 60. The guard 60 may have an amplifier housingformed integrally therewith, as in the case of the guard 22, Fig. 1, butthis housing and the hinges do not appear in Figs. 5 and 6 because ofthe fact that in these views the parts are rotated ninety degrees fromthe position in which the corresponding parts are seen in Fig. 1.

The shaft of the motor is indicated at 56, Fig. 5, where it will be seenthat the shaft is hollow; that is, there is an axial bore extendingclear through the shaft. Beneath the motor there is a lamp housing 6|,containing the lamp 62. The lamp housing maybe independently supported,or may be attached to the motor as shown. The lamp is mounted in asuitable socket connected to a source of current and is located inalignment with the motor shaft.

The chuck for holding the fuse is mounted on the upper end of the motorshaft 56 and comprises the base member 51, a cup-shaped member 63secured thereto by screws, as indicated, and a locking cap 58. Inside ofthe cap 58 there is a slidable member 59 which is forced in a downwarddirection by means of a plurality of springs such as 64. When the cap isremoved from the chuck the downward movement of member 59 is limited bya stop pin 65.

A fuse is indicated at I4. The cap 58 having been removed, the fuse isplaced in the seat 66 of the chuck and is rotated until the positioningnotch or recess 68 is in alignment with a corresponding projection (notshown) with which the seat is provided, whereupon the fuse will enterthe seat properly. The cap 58 is then placed on the chuck and is rotatedif necessary to enable the pins such as 69 to enter the slots such asI0. The top of the fuse is now engaged by the seat 61 formed in thesliding member 59, which moves upward in the cap as the latter ispressed down to engage and lock the bayonet joints. This operation isthe same as described in the case of the cap 8, Fig. 1; that is, the capis pressed down as far as it will go and is then rotated in the properdirection to lock the joints. The fuse is now firmly held between theseats 66 and 61.

The optical system comprises the lamp 62, Fig. 5, the photo-cell 34,located just above the guard as shown in Fig. 6, and a system of mirrorsby means of which the light is directed from the lamp to the photo-cellover a path which is intersected by the oscillatable pallet arm of thefuse. The fuse is the same as the fuse shown in Fig. 2, except that theplates 16 and 11 have slots milled in them, as shown in Fig. 7. Theseslots are in alignment with the opening such as 48 in the top plate ofthe fuse and form a light passage which is closed by the pallet arm suchas 44 when the pallet arm is in its mid-position. 1

The mirror system includes a mirror 12 which is secured to the chuck andreceives light coming through the hollow shaft of the motor. Op-v positethe mirror I2 there is a slot II milled in the chuck as shown, and inthis slot there is secured a mirror 13, which receives light, reflectedfrom the mirror I2 and reflects it to a mirror 14. The latter mirror issecured to the inside wall of the cap 58 and reflects the light throughthe fuse (when the previously described light passage is not closed bythe pallet arm) to the mirror I5, which in turn reflects the lightthrough an opening in the top of the cap to the photocell 34'. Themirrors may be made of metal and have polished reflecting surfaces cutat the proper angles to reflect the light over the path described. Theresult is that the photocell is able to see the lamp, in a manner ofspeaking, except when the view is obstructed by the pallet arm in thefuse.

The arrangement shown in Figs. 5 and 6 may be used alternatively withthat shown in Fig. 1. Each arrangement has certain advantages. Theoptical system of Fig. 1 is shorter and has fewer parts than thatemployed in Fig. 6. 0n the other hand, the optical system shown in Fig.6 dispenses with a reflecting surface on the fuse, and the lamp is solocated that its connecting wires are not crossed by the light path asthe fuse is rotated. The arrangement to be used therefore rests in thesounder judgement of the designer or manufacturer, as influenced by therespective advantages of the two arrangements, and perhaps by otherfactors which need not be discussed.

Referring now to the circuit diagram, Figs. 8 and 9, the apparatus showntherein will be briefly described. I

At the left of Fig. 8 the motor 2 and chuck 4 for rotating a fuse I4 areshown diagrammatically, together with the essential parts of the opticalsystem such as the lamp 30, mirror 36, and photo-cell 34. These are thesame parts that are shown in Fig. 1. It will be understood that themodification shown in Figs. 5 and 6 may be substituted for Fig. 1 ifdesired.

The photo-cell 34 is located in the guard, as shown in Fig. 1, and ispreferably of the type which includes a cathode in the form of a plateI00 and an anode in the form of a rectangular frame IOI.' The light beampasses through the frame and thus reaches the cathode withoutinterference from the anode.

The reference character IIO indicates a preamplifier tube, preferablytype 6C5, which is also located in the guard, or rather in the housingwhich forms part of the guard. A conductor I08 supplies plate voltage tothe tube I I0 and also sup plies anode potential for the anode IOI ofthe photo-cell 34, to which it is connected by way of resistors I08 andI02. The photo-cell circuit thus includes the grounded cathode I00, theanode IOI, resistors I02 and I06, and conductor I08,

which is connected to the +B lead. The photocell circuit is coupled tothe grid of tube III) by means of a condenser I03, said grid beingprovided with a grid leak I04. A cathode resistor I0! is provided inorder to give the grid of the tube the proper negative bias. CondenserI05 is a bypass condenser.

The reference character I I I indicates an amplifier tube, which may bea type 6J7G pentode. The grid of tube I I I is coupled to the platecircuit of the preceding tube I I 0 by means of a condenser I09. It maybe pointed out here that conductor I08 is preferably shielded after itleaves the guard, as indicated by the dotted lines. shielding and theguard should be grounded. The circuit arrangement for tube III isotherwise conventional and need not be described in detail. The nexttube, indicated at I20, may be a type 605 tube and functions as anamplifier. The grid circuit of tube I20 includes a filter element comvprising the inductance I I4 and condenser I I5 and is coupled to theplate circuit of the preceding The The lower half of Fig. 8 shows thecontrol cir-' cuits for the motor 2, which will now be describedbriefly.

The reference character S indicates a switch for starting the motor andis preferably a foot switch arranged so as to be conveniently accessibleto the operator. The switch which includes contact spring 21 controlledby the guard is connected in series with the switch S, as shown.

The tube I38, which may be a type 6C5 triode, and its associated circuitelements constitute a time delay device, the operation of which will bedescribed presently. A similar tube I48 and associated circuit elementsconstitute another time delay device. Relays I44, I46, and I52 arealternating current relays and operate on l10-volt commercialalternating current which is supplied over conductors I30 and I3I.Relays I39 and I49. are direct current relays and are connected in theplate circuits of tubes I38 and I48, respectively.

The rectangle indicated by the numeral I60 represents a motor generatorset which may be of any well known type. The three phase output of thisset is used to start the motor 2 and bring it up to its approximaterunning speed. The rectangle IBI represents a power amplifier or othersource of three phase power having a constant frequency which is usedfor running the motor 2 during timing operations. A suitable poweramplifier for this purpose is shown in the patent to Wickham, No.2,333,502, granted Nov. 2, 1943. The motor generator set is used forstarting because the motor 2 has to be accelerated very rapidly,requiring a considerable amount of power, which is provided moreeconomically by a motor generator set. Ordinary commercial power cannotbe used because its frequency is too low to run the motor at the properspeed. The arrangement shown permits the use of a power amplifier ofmuch smaller capacity than would be required if a separate source ofpower for starting were not prow'ded, and is to be preferred mainly forthis reason.

Referring now to Fig. 9, the upper half of this drawing shows a fourstage frequency divider, such as is disclosed in Patent No. 2,304,813,Dec. 15, 1942, and comprising the tubes 200, 20I, 202, and 203. Each ofthese tubes may be a type 6N7 double triode, having suitable circuitconnections whereby it operates as a multivibrator. The first stagemultivibrator is controlled over conductor I26 from the plate circuit oftube 525, Fig. 8.

The output from the last multivibrator stage is used to'control the gridof tube 206, to which it is applied through a condenser 204 and resistance 205. Tube 206 may be a gas filled tube, type 631P1.

The tube 206 is used to control a recording device, which maybe of thetype which employs a toothed disk rotating at a constant predeterminedspeed and cooperating with printing means controlled by the impulses tobe recorded to mark a moving strip of tape. This device will be brieflydescribed.

The reference character 22I indicates a two phase synchronous motor,which rotates the toothed disk 235. The tape 230 is supplied from theroll 228 and is fed past the edge of disk 235 by a feed mechanismcomprising the driven roller 224 and a. friction roller 225. Suitableguiding means (not shown) may also be employed to give the tape a curvedformation at the point where It passes the edge of the disk. driven by amotor 220 through the medium of suitable speed reducing mechanismcomprising the worm 222 and gear 223. The roller 22! is normally heldvslightly above roller 224 so that the feed mechanism is inoperative toadvance the tape 230 which rests loosely on the roller 224. Roller 225is lowered to press the tape against roller 224 and start the feed bymeans of a magnet 232, which also controls the circuit of motor 220 atcontact springs 23'! and 230. The tape speed may be one inch per second.The tape is marked by means of a ribbon 245, which is fed across thetape where it passes the disk 235, and a printer bar 234. The latter hasa curved lower edge and is actuated by the magnet 23I.

The motor 22I is supplied with power from a standard frequency sourcerepresented by the rectangle 2I6, which also supplies power to the motor220. The standard frequency source may consist of a crystal oscillator,a frequency divider, and suitable amplifiers.

The tube 250 is an amplifier tube and is controlled over conductor I2Ifrom the P e 01 cuit of tube I20, 8. The reference character 25Iindicates a potentiometer, which is used for adjusting the controlvoltage applied to the grid of tube 250. -Tllbe 25I is also an amplifiertube and has its grid coupled to the plate circuit of tube 250 by meansof a condenser 252. The plate circuit of tube 25I includes a relay 253,which controls the recording device.

The various tubes in Figs. 8 and 9, except tubes I38 and I40, aresupplied with plate current from a suitable source of direct currentconnected to conductor 260, as will readily be understood. It will alsobe understood that known arrangements are provided for supplying currentto the cathode heater circuits indicated throughout the drawings. a

The apparatus having been described, the operation of timing a fuse willnow be described.

For this purpose it will be assumed that the i switch S2, Fig. 9, isclosed and that the motor 22I is running. Motor 220 is standing still,as its circuit is open at contact springs 23? and 233. At contactsprings 231 and 239 the resistance 23-6 is connected in place of themotor 220 and places an equivalent load on the standard frequencysource.

The fuse I4 is placed in the chuck in the manner described in detail inconnection with Fig. 1 and is locked in place by the cap 8. The guard 22is then lowered to the position in which it appears in Fig. 1, thusenclosing the chuck and fuse as a protection to the operator andbringing the various parts of the optical system into operative relationto the fuse. The lowering of the guard also actuates the pin 29 andcloses contact springs 21 and 28. This operation, by means of anotherpair of contact springs, may close a circuit for lamp 30, although thelamp may be continuously lighted while the timing operations are goingon, as previousl intimated. No light from the lamp reaches thephoto-cell because the light path is interrupted by the pallet arm 44 ofthe fuse.

The operator may now close the switch S, thereby closing a circuit forthe relay I46, said cir-. cuit extending from conductor I30 by way ofswitch S, contacts 21 and 28, contact I42 of relay I39, and winding ofrelay I46 to conductor I3I. The conductors I30 and I3I are connected toa suitable alternating current supply line'and The roller 224 istentiometer I35 to conductor I30.

relay I46 is accordingly energized, opening its contact I41 for apurpose which will be described, and at its three upper contactsconnecting the motor generator set to the three phase line I62, I63, andI64 extending to the motor 2. The motor is thus started and comesrapidly up to speed,

- the period of acceleration being about two seconds or slightly less.

The motor rotates the fuse by means of the chuck in which it is held andthe fuse begins to run, transmitting light impulses to the .photocell34. The explanation of the effect of the light impulses and theoperations controlled thereby willbe deferred until the furtheroperation of the motor control circuits has been explained.

As previously mentioned, the tube I38 and associated circuits operate asa. time delay device. The plate of the tube is connected to conductorI3I by way of rela "I39. The cathode is normally open except for itsconnection to conductor I3I by way of resistance I31 and consequent- 1yno plate current can flow through the tube and relay I39 is normallydeenergized. The grid of the tube is connected by way of resistor I32and resistor I33 to a bridge comprising resistor I36 and potentiometerI35. At times hen the conductor I30 is positive, therefore, our nt flowsover a path which may be traced from conductor I3I by way of resistanceI31, cathode and grid of the tube, resistors I32 and I 33, and po- Thevoltage in this circuit depends on the adjustment of the potentiometer,although it will be obvious that at times when conductor I30 is positiveand conductor I3I is negative any point on the potentiometer will bepositive with respect to conductor I. |3II1 view of the flow of currentover the above described circuit including the grid of the tube there isa fall of potential across the resistor I33 and the condenser I34becomes charged, the polarity being such that the upper terminal of thecondenser is charged negatively. The condenser cannot discharge duringthe half cycle periods when conductor I30 is negative and conductor I3Iis positive because the tube cannot pass current from grid to cathode. Aslight discharge does occur during each such period through resistanceI33, but this resistance is very high and the amount of discharge isnegligible. The foregoing describes the conditions when the switch S isopen. When the switch S is closed, the relay I46 is energized aspreviousl /described. At the same time the conductor I3'II is connectedto the oathode of the tube. This completes the cathode plate circuit ofthe tube, and current would flow during the half-cycle periods whenconductor I3I is positive, except for the fact that the grid of the tubehas a negative potential on it due to the charged condenser I34. Thecondenser can receive no further charging current now, since the cathodeis connected to conductor I30, and slowly discharges through resistorI33. As the condenser discharges the negative potential on the grid islowered gradually, and the grid eventually begins to swing positive withrespect to the cathode during eachhalf-cyde period in which conductorI3I is positive. During these periods, therefore, the tube passescurrent and relay notwithstanding the mtermittent current which itreceives.

The tube I38 introduces a delay between the closure of the switch S andthe energization of relay I39. The amount of the delay is preferablyabout seconds, corresponding to the time required for the motorgenerator set to bring the motor 2 up to speed, and is regulated byadjustment of the potentiometer I35. This device adjusts the voltage towhich the condenser is charged and accordingly adjusts the time requiredfor it to discharge.

When relay I39 energizes, it breaks the circuit of relay I46 at contactI42 and closes the circuit of relay I44 at contact I M. Relay I46accordingly deenergizes and relay I44 energizes, with the result thatthe motor generator set is disconnected from the motor 2 and the poweramplifier is connected to the motor in place thereof. This switchingoperation takes place in such a manner that the motor generator set andpower amplifier are not connected together;

' that is, relay I46 deenergizes an instant before relay I39 isenergized. The condenser I40 is effective to produce a steadyenergization of the relay I44 energizes. The proper timing of the relayscan be secured by adjustment, although a known form of mechanicalinterlock between the relay armatures can be used as an additionalprecaution if desired. Fusing of the leads to the power amplifier isalso recommended as a safety measure to prevent any possibility ofdamage to the equipment.

With relay I44 in energized position the power amplifier supplies powerto the motor 2 and the motor accordingly runs at a constantpredetermined speed, as determined by the frequency of the amplifieroutput, which is accurately controlled in some suitable manner, as by acrystal oscillator. the motor runs at a speed of 16,200 R. P. M., butother speeds may have to be used for other types of fuses, and it mayeven be desirable to test certain fuses at different rotational speeds.The essential feature involved here is that the rotational speed isexactly predetermined and is maintained constant at the desired value.

When relay I44 energizes, it also opens its contact I45. This contact isconnected in series with contact I 41 in the cathode circuit of tubeI48. The tube I48 is wired up similar to tube I38 and constitutesanother time delay device. Before the switch S is closed, the cathode ofthe tube is connected to conductor I30, the tube passes current, andrelay I49 is maintained energized. The operation of switch S is followedby the energization of relay I46, which opens the circuit of the cathodeof tube I48. Relay I 44 also opens this circuit, so that while theswitch S is in operated position tube I48 is in non-conducting conditioninsofar as the cathode plate circuit is concerned and relay I49 isdeenergized. At its contact I 5| relay I49 prepares a circuit for relayI52, which is held open for the time being at contact I45 of relay I44.

The fuse I4 is now being rotated at the required speed, and theclockwork mechanism therein has started to operate. The oscillations ofthe pallet arm permit light to pass from the lamp 30 by way of thereflecting surface 43 in the fuse (see Fig. 3), and the annular mirror36, to the cathode I00 of the photo-cell, .but the light is interruptedduring each beat of the pallet arm as it passes through itsmid-position. The photo-cell thus receives light interrupted at the beatfrequency of the fuse, which in this case is assumed to be 344 beats persecond, and

In the case being described" these other components are relatively smallas compared to the 344 cycle component.

The photo-cell circuit extends from ground by way of the cathode I00,anode IOI, resistance I02 and resistance I05 to the conductor I03,

which connects to the +13 lead 260, Fig. 9. 4

Variations in the current in this circuit produce changes in potentialat the anode I III, which are transmitted to the grid of tube IIO bymeans of the condenser I03. The tube IIO functions as an amplifier andits output, including a principal component having a frequency of 344cycles per second, is further amplified by the tube III. The operationof these tubes is well known and need not be described in detail.

The coupling circuit between tubes III and I includes a filter networkcomprising the inductance H4 and condenser II5, which is tuned toresonance at a frequency of 344 cycles ,per second. The voltageimpressed on the grid of tube I20 depends on the impedance of thisfilter network, which is very high at a frequency of 344 cycles persecond and comparatively low at higher and lower frequencies. The 344cycle component of the output of tube III therefore produces relativelylarge voltage changes at the grid of tube I20, whereas other componentsproduce little effect. and are substantially eliminated.

The output of tube I20, which also functions as an amplifier, would beadequate without further amplification, but the voltage of the output issubject to variations in amplitude due to differences in the fuses andother causes, and accordingly the voltage regulator tube I23 isprovided. The output circuit of tube I20 is coupled to the grid of tubeI23 through the highresistance I22, having a value of about ten megohms.This resistance is so high, as compared to the cathode to gridresistance of the tube, that the potential on the grid can never becomemore than slightly positive with respect to thecathode. The platecurrent at tube I23 therefore changes between zero and a small value,regardless of the amplitude of thecontrol voltages applied to the gridfrom the output circuit of tube I20, and the output of tube I23 has afiat topped wave shape of substantially constant amplitude.

The output of the voltage regulator tube I23 is applied to the grid oftube I25, which functions as an amplifier and makes up for the losses attube I23. Tube I25 therefore supplies a reliable signal derived from therotating fuse,

having a frequency of 344 cycles per second and vibrator is known andhence need not be described in detail. It will sufllce to say that thefirst multivibrator 200 is controlled-over conductor I20 and oscillatesat a frequency of 172 cycles per second, thus dividing the 344-cyclesignal frequency by 2. The second multivibntor 20l is controlled fromthe first, and oscillates at a frequency of 57% cycles per second,dividing by 3. The third multivibrator 232 divides by 3 also andoscillates at a frequency of 19% cycles per second. The fourthmultivibrator 2 divides by 2 and oscillates at a frequency of 975 cyclesper second, which is the output frequency of the frequency divider.Considered as a whole, the frequency divider divides by 36; that is, theoutput frequency is ,5 that of the original signal current generated bythe photocell in response to operation of the fuse.

It will be understood that the fuse signal current, referred to hereinas having a frequency of 344 cycles per second, has exactly thatfrequency only if the particular fuse from which the current isgenerated is running at exactly the proper rate. If the rate isincorrect, the frequency of the signal current will not be exactly 344cycles per second and the frequency of the output from the frequencydivider will vary accordingly. This output frequency is compared with astandard frequency by the recording device in order to determine if therate of the fuse is correct, or is fast or slow.

The output of the frequency divider has a suitable frequency forcontrolling the recording device, but otherwise is entirely unsuitableand has to be converted into a train of short direct current impulseshaving the same frequency. It is for this purpose that the tube 2" isprovided. The last stage multivibrator is connected by way of condenser20! and resistor 205 to the grid of tube 206, whereby control voltagesmay be applied to the grid. Tube 206 is normally inoperative, however,because the grid is grounded at contact 255 of relay 253.

Tube 200 is rendered operatlve by opening of the ground connection toits grid at the time the motor 2 is switched over to the poweramplifier. At this time the fuse will be operating and control voltageswill be delivered over the conductor I21 to the grid of tube 250. Thistube functions as an amplifier and has its output circuit coupled t thegrid of tube 25I, which also functions as an amplifier. tube 25Iincludes the relay 253 and is closed at contact I43 of relay I39 whenthe latter relay operates. Relay 253 is accordingly energized at thesame time as relay I. To prevent chattering of relay 253 its winding isshunted by a condenser. The proper operation of tubes 250 v and 25I issecured by adjustment of the potentiitive with respect to the grid,which is normally a relatively constant amplitude. I

The output of tube I25 is used to control the first stage multivibrator200 of the frequency divider, Fig. 9. The frequency divider is providedfor the purpose of reducing the frequency of the signal generated byoperation of the fuse to a lower frequency which is suitable foroperating the recording device. The operation of a multioutput from thefrequencydivider.

at ground potential, and insures a positive release of relay 253 whensignal current ceases.

When relay 253 energizes, contact 255 is opened and tube 206 is placedunder the control of the Tube 203 has two control grids. The upper gridis main- The plate circuit of of a potentiometer consisting of resistors201 and 208. The potential on the lower grid, is determined by thecontrol voltage received from the frequency divider. The output of thefrequency divider has a wave shape characteristic of multivibrators;that is, the negative half-waves are of considerable amplitude and havea steep 'wave front. Each negative half-wave therefore drives the lowergrid to a potential which is considerably below ground potential and farenough below'the potential on the upper grid so that the difierence ingrid potentials is sufficient to start th discharge of the tube.

When the tube 206 becomes conductive in the manner explained above, thecondenser 2I0 discharges quickly over a-path which includes the cathodeand plate of the tube and the printer bar operating magnet 23I, thusfurnishing a short, powerful energizing impulse to the magnet, thecondenser 2I0 having sufficient capacity for the purpose. The dischargeof the condenser reduces the voltage at the plate of tube 206 to such alow value that the discharge through the tube cannot be maintained andit becomes non-conductive. The condenser 2I0 now charges up in serieswith the resistor 2I I, the value of the resistor being such that thecondenser becomes nearly fully charged by the time the next negativehalf-wave of control voltage appears at the lower grid of tube 206. Thetube 206 then becomes conductive again and the condenser 2I0 is againdischarged through the magnet 23I. The operation of tube 206 continuesin this manner as long as the control voltages are supplied from thefrequency divider.

From the foregoing it will be seen that the frequency divider output,having a frequency of 954, cycles per second, is converted by means ofthe tube 206 into a train of direct current impulses having the samefrequency, which are effective to actuate the printer bar magnet 23I.These operations of the magnet result in the printing of a record of theoperationof the fuse, as will now be explained.

When relay 253 energizes, it also closes a circuit for magnet 232 atcontact 256. Magnet 232 accordingly energizes and by means of itsarmature 226 presses the roller 225 against the tape 230 at the pointwhere the tape passes the roller 224. Armature 226 also actuates thecontact spring 231, which disconnects the load resistance 236 andconnects the motor 220 in place thereof. The motor 220 now starts to runand rotates the roller 224, which begins to feed the tape 230 along pastthe edge of the rotating toothed disk 235. The recording device is nowin operation. Each time the printer bar 234 is depressed by theenergization of magnet 23I, it cooperates with a tooth of the rotatingdisk 235 to print a mark on the tape 230, and these marks are spacedapart in a row due to the linear feed of the tape past the edge of thedisk.

The speed of the motor 22I is constant and has such a value that anexactly even number of teeth will pass the tape 230 between successiveactuations of the printer bar, provided the fuse being timed is runningat the correct rate. The tooth speed may be, for example, 172 teeth persecond. There may be 12 teeth on the disk, in which case the motor 22Iwill run at a speed of 860R. P. M. The output frequency of the standardfrequency source is such that the motor is run at the correct speed.

The number of teeth which pass the tape between successive actuations ofthe printer bar,

I another fuse is inserted.

with the above assumed tooth speed of 172 teeth per second, is 18. Thisfollows from the fact that the signal frequency is 36 times the printerbar frequency and from the further fact that the assumed tooth speed isone-half the signal frequency.

The direction of the row of marks which is printed on the tape indicatesto the operator whether the rate of the fuse is correct or not, and ifthe rate is incorrect, whether it is fast or slow. If the rate iscorrect, the teeth of disk 235 which are used on successive printingoperations will be in exactly the same transverse position relative tothe tape when the printing operations take place, and the resulting rowof marks will be parallel to the edge of the tape. If the rate of thefuse is slow, the disk 235 will gain a little between successiveprinting operations and assuming clockwise rotation of the disk asviewed from the front, the row of marks will trend to the right.Similarly, if the rate of the fuse is fast, the disk 235 will graduallyfall behind, and the row of marks will trend to the left. In either casethe sharpness of the trend, or the size of the angle which the row ofmarks makes with the edge of the tape, is a measure of the amount oferror in the rate.

Since the marks are printed at the rate of 9% marks per second, it willbe clear that in two or three seconds enough marks will have beenprinted so that the operator can determine the direction of the rowf Theoperator then stops the timing operation by releasingthe switch S.

Upon the opening of the switch, the time delay device including tube I38reverts to its normal condition, tube I38 ceases to pass current, andrelay I39 is deenergized. The deenergization of relay I39 opens thecircuit of relay I44, which deenergizes also and disconnects the poweramplifier from the motor 2. Relays I44, I46, and I49 now being indeenergized condition, a circuit is completed for relay I52, whichenergizes and at its contacts I53 and I54 connects a source of directcurrent to the power leads I63 and I 64 extending to the motor. Thisoperation brings the motor quickly to a stop. The closure of contact I45of relay I44 not only completes the circuit of the braking relay I49 asdescribed, but also connects conductor I30 to the cathode of the tube I48. This tube operates in the same way as was described in the case oftube I38 and after several seconds, therefore, it begins to pass currentand relay I49 is energized. The circuit of relay I52 is thus broken atcontact I5I and relay I52 deenergizes, disconnecting the direct currentsource from the motor. The time delay device including tube I48 shouldbe so adjusted that the braking current is applied to the motor for aperiod of time just sufficient to stop the motor reliably.

The operator now raises the guard 22 to expose the fuse and chuck.Further operations depend on whether the rate of the fuse just timed iscorrect or not. If the rate was found to be correct, the fuse is removedfrom the chuck and It may be assumed, however, that the fuse was foundto be slow, as indicated by a row of marks 246, which trends rapidly tothe right.

The operator therefore makes an adjustment of the fuse such as to makethe clockwork mechanism run at a faster rate. The adjustment having beencompleted, the operator lowers the guard and then depresses the switch Sto start recording device.

another timing operation. It will be noted that the operation of theswitch while the guard is up will have no effect, since the contacts 21and 28 must be closed also before the timing operation can be started.

It may be assumed that on the second timing operation performed on thisparticular fuse a row of marks such as shown at 241 is printed. This rowtrends to the left slightly, indicating to the operator that theadjustment was carried too far, causing the fuse to run slightly fast.Another adjustment and timing operation is therefore required. It may beassumed that the next time the fuse is tested its rate is found to becorrect, as indicated by the row of marks at 8, which is parallel to theedge of the tape.

The switch SI, Fig. 9, is adapted to close a circuit to an oscillographwhich may be provided for the purpose of indicating the rate of fusesoccasionally met with, which are so far oif'in rate that they cannot betimed to advantage with the The operation of an oscillograph for thispurpose is known and hence will not be described.

It will be seen from all the foregoing that a new and improved timingapparatus has been devised which is particularly well adapted for timingfuses of the type described herein while the same are undergoingrotation at high speed. The utility of the apparatus is not necessarilylimited to the timing of fuses, however, as it may be used in anysituation where the rate of an oscillating member is to be determinedwhile it is rotating, suitable modifications being made if necessary toadapt the apparatus to the circumstances of each case. It will beunderstood also that, whereas certain specific apparatus and circuitshave been described herein, this has been done merely for the purpose ofacquainting the public with a method of practicing the invention and notwith the intention of limiting the invention to any particularembodiment thereof. I do not therefore wish to be restricted to theprecise form of the invention which is shown and described herein, butdesire to include and have protected by Letters Patent all forms andmodifications of the invention that come within the scope of theappended claims.

I claim:

1. Apparatus for timing a fuse of the clockwork type having a partsubject to oscillatory motion, comprising means for rotating said fuse,a light source, a photocell, means including a mirror whereby saidphotocell is placed under the control of said light source over a lightpath which rotates in synchronism with said fuse and which isperiodically interrupted by said part while oscillating, means includingsaid photocell for generating periodic voltages having a frequencybearing a predetermined relation to the oscillatory frequency of saidpart, and means for comparing the voltage frequency with a standardfrequency.

2. Apparatus for timing a device having an oscillating member while thedevice is in rotation, comprising means for projecting a beam of lightacross the path of said oscillating member, said beam intersecting saidpath at a point outside the axis on which said device is rotating, meansfor rotating said beam in synchronism with said device and about thesame axis so that the relation between the beam and the oscillatingmember will be unaffected by rotation of said device, a photocell forreceiving said beam when the same is not intercepted by said member,

meansincludingsaid photocell for generating periodic voltages having afrequency bearing a predetermined relation to the frequency of saidmember, and means for comparing the voltage frequency with a standardfrequency.

3. Apparatus for timing a device having a part subject to independentperiodic .lnotion while the device as a whole is subjected to rotation,comprising means for rotating said device, means for projecting a beamof light along a path which rotates in synchronism with said device andwhich is so arranged that the beam isthe device as a whole is beingrotated, comprising means for rotating said device, including a chuckfor holding thev device while it is rotating, a photocell, meansincluding a mirror for passing a beam of light through said chunk anddevice tosaid photocell along a line which rotates in synchronism withsaid device and which is periodically cut by said part whileoscillating, means including said photocell for generating periodicvoltages having a frequency bearing a predetermined relation to thefrequency of said oscillatory motion, and means for comparing thevoltage frequency with a standard frequency.

5. Apparatus for timing a fuse of the clockwork type having a partsubject to oscillatory motion, comprising means for rotating said fuse,a light source, a photocell, a means including an annular mirrorsurrounding said fuse and cooperating with a reflecting surface of saidfuse for placing said photocell under the control of said light sourceover a rotating light path which is periodically intercepted by saidpart while oscillating, means including said photocell for generatingperiodic voltages having a frequency bearing a predetermined relation tothe frequency of said oscillatory motion, and means for comparing thevoltage frequency with a standard frequency.

6. Apparatus for timing a device having an oscillating member while thedevice is rotating, comprising means for projecting a beam of lightalong a line which coincides in part with the axis of rotation of saiddevice and which includes a section which is non-coincident with saidaxis and crosses the path of said oscillating member, means for rotatingsaid beam about said axis and in synchronism with said device, aphotocell on which the beam impinges when not intercepted by saidmember, means including said photocell for generating periodic voltageshaving a frequency bearing a predetermined relation to the oscillatingfrequency of said member, and means for comparing the voltage frequencywith a standard frequency.

7. In a fuse timing apparatus, a chuck for holding a fuse, a motor forrotating said chuck, a passageway for light extending through the motorshaft and across the path of an oscillating part of a fuse held in thechuck, a source of non-parallel light rays for continuously directinglight along said passageway, a photocell on which light coming throughsaid passageway impinges. means including said photocell for generatingperiodic voltages having a fre-- quency bearing a predetermined relationto the frequency of said oscillating (part, and means for comparing saidvoltage frequency with a standard frequency.

8. Apparatus for timing a fuse having a part subject to oscillatorymotion, comprising a chuck for holding said fuse, a motor having ahollow shaft for rotating said chuck, a source of light and a' photocelllocated on the rotation axis and on opposite sides of the chuck andmotor assembly, means for passing a beam of light from said sourcethrough the motor shaft, chuck, and fuse to said photocell along a, linewhich departs from the rotation axis to cross the path of saidoscillating part, and electrical means controlled by said photocell forcomparing the frequency of said oscillatory motion with a standardfrequency.

9. In a fuse timing apparatus, a rotatable chuck comprising means forholding a fuse, a light source, a photocell, means including a. mirroreffective while a fuse is being rotated by said chuck whereby saidphotocell views said light source over a path having a section whichrotates with said fuse and which is periodically interrupted by anoscillating part of said fuse, and means including said photocell forgenerating periodic voltages responsive to the interruption of saidlight path.

10. In a fuse timing apparatus, a rotatable chuck for holding a fuse,means cooperating with a reflecting surface of a fuse being rotated bysaid chuck for forming a radial beam of light passing through an openingin the side of said chuck, said light being periodically interrupted bya moving part of the fuse, a photocell, and an annular mirrorsurrounding said chuck for reflecting said light beam to said photocell.

11. In a fuse timing apparatus, a rotatable chuck for holding a fuse, aphotocell positioned on the rotation axis of the fuse, a lamp located onsaid axis between the photocell and the fuse, means including a lightpassage extending through the fuse and a mirror for passing a beam oflight from said lamp to said photocell, and transparent suporting meansfor said lamp to permit passage of said beam.

12. In a fuse timing apparatus, a rotatable chuck for holding a fuse,said chuck having a passageway for light which coincides in part with alight passage extending through a fuse which is held in the chuck, aremovable protective guard adapted to enclose the chuck and fuse, and anoptical system including a lamp and a photocell mounted on the inside ofsaid guard and also including a path for light extending from said lampthrough said passageway to the photocell when the guard is in protectiveposi tion with respect to said chuck and fuse.

13. In a fuse timing apparatus, a chuck for holding a fuse, means forrotating said chuck, a source of light, a mirror system in said chuckfor receiving light from said source and for directing it over a pathwhich crosses the plane of oscillation of an oscillating member in saidfuse and leaves the chuck along its axis of rotation, and a photocelllocated on said axis for intercepting light which is transmitted oversaid path and not intercepted by said oscillating member.

14. In a fuse timing apparatus, means including a chuck and a motor forrotating a fuse, a protective guard adapted to enclose said chuck andfuse while the same are rotating, photoelectric means in said guard forgenerating periodic voltages responsive to operation of 'said fuse,means also contained in said guard for amplifying said periodic,voltages, and a partition dividing the interior of said guard into twocompartments, one compartment containing the said chuck, fuse,andphotoelectric means and the other compartment containing the saidamplif ing means.

15. In a fuse timing apparatus, means including a chuck and a motor forrotating a fuse, a protective guard adapted to enclose said chuck andfuse while the same are rotating, means including a photocell insidesaid guard for generating periodic voltages responsive to operation ofsaid fuse, means including a space discharge device inside said guardfor amplifying said voltages, an amplifier outside said guard includinga second space discharge device, and asingle conductor extending betweenthe guard and said amplifier for supplying anode potentials to saidphotocell and said first discharge device and amplified control voltagesto the grid of said second space discharge device.

1 16. Apparatus for use in testing a device which includes a part havingan orbital motion and a periodic oscillatory motion, comprising a lightpath including a section rotating in the orbit of said part in phasetherewith and at the same speed, whereby said light path is periodicallymodified by the oscillatory motion of said part, means for transmittinglight over said path, a photocell on which the light transmitted oversaid path impinges, and means including said photocell for generatingperiodic voltages having a frequency dependent upon the frequency ofsaid oscillatory motion. I

17. In a fuse timing apparatus, means for rotating a fuse, a photocelllocated on the rotational axis of said fuse, a light source also locatedon said rotational axis, said fuse including means cooperating with saidlight source to transmit a modulated light beam in a direction at anangle to the rotational axis of the fuse, and means including an annularmirror for intercepting said beam in all positions which the fuseassumes while rotating and for reflecting the intercepted beam to saidphotocell.

18. In a fuse timing apparatus, a rotatable chuck for holding a fuse, anannular mirror surrounding sald chuck, means for projecting light tosaid mirror over a path which is adapted to be influenced by operationof the fuse responsive to rotation thereof by said chuck, and aphotocell to which the said mirror reflects the light received over saidlight path.

19. In a fuse timing apparatus, an optical system including a lightsource and an annular mirror, a chuck for supporting a fuse on the axisof said mirror, means for rotating said chuck to cause the fuse totransmit a rotating beam of light from said source to said mirror, saidbeam being periodically influenced by operation of the fuse whileundergoing rotation, and a photocell to which the said beam is reflectedby said mirror in all angular positions of said fuse.

20. For use in timing mechanical fuses, a rotatable chuck comprising twomanually separable parts, of which one part includes a seat for a fuseand the other part includes means for clamping the fuse in said seat,said chuck also including reflectors mounted on said parts and includedin an optical system for directing a beam directing a beam of lightthrough said shaft and chuck, and reflecting means in said chuck fordisplacing a section of said beam so as to cross the path of a movablemember forming part of a device held in said chuck.

22. For use in timing mechanical fuses, a rotatable chuck comprisingmeans for holding a fuse which has a light passage adapted to beinterrupted by an oscillating part of the fuse, an opening in the sideof said chuck for the passage of light, and means included in the chuckto aid in orienting a fuse inserted therein so that the said lightpassage is aligned with said open .ing.

23. For use in testing mechanical fuses, a ro tatable chuck comprisingmeans for holding a fuse, said fuse being of the type which includesmeans for projecting a light beam at an angle to the rotational axis ofthe chuck when the fuse is held therein, said light beam being under theinfluence of a moving part of the fuse, an opening in the chuck forpassage of said beam, and means for preventing seating of the fuse inthe chuck unless the fuse is so oriented that the said light beam canpass through said opening.

24. For use in testing mechanical fuses, a rotatable chuck comprisingmeans for holding a fuse, said fuse having a light passage adapted to beinfluenced by a moving part of the fuse, said chuck also having a lightpassage including openings for the entrance and egress of light, andmeans in said chuck cooperating with said fuse to aid in orienting thesame when inserted in the chuck so that the two light passagessupplement each other to form a continuous light passage.

25. For use in testing mechanical fuses, a rotatable chuck including aseat for a fuse, means for holding the fuse in said seat, a lightpassage controlled by a moving part of the fuse when the fuse isoperating and adapted to be completed only when the fuse occupies aparticular angular position in said seat, and means in said chuck to aidin orienting the fuse to said position when it is placed in said seat.

26. For use in testing mechanical fuses, a rotatable chuck comprising abase member, a hollow cap member, means for locking the cap member tothe base member, oppositely disposed seats for a fuse located in saidbase and cap members, respectively, one of said seats being movable, andresilient means for urging the movable seat in the direction of theother seat.

27. For use in testing mechanical fuses, a rotatable chuck comprising abase member having a seat for a fuse, a removable cylindrical cap memberadapted for telescopic cooperation with said base member to enclose afuse seated thereon, a second seat for the fuse carried by said capmember and adapted to engage the fuse when the cap member is placed onsaid base member, means permitting one of said seats to yield when thecap member and base member are telescoped together, and means forsecuring the cap member to the base member.

28. In a fuse timing apparatus, a rotatable chuck comprising means forholding a fuse, said chuck and the fuse which is held therein having apassageway for light which rotates with the fuse and which isperiodically interrupted by a moving part of the fuse when the chuck isrotating, a photocell, means incluing a mirror for directing lightthrough said passageway to said photocell with the chuck in any angularposition, and means including said photocell for generating periodicvoltages responsive to the periodic interruption of said light passagebythe said moving part of the fuse.

THOMAS B. GIBBS.

